A list of a series of 2462 ssc's was made by studying the 100-year magnetic records in two antipodal sub-auroral observatories and in one low-latitude observatory. Various statistical results are set forth. The negative correlation between ssc amplitude and rise time postulated by Dessler et al. (1960) seems to be true for the more rapid ssc's (1-4 min). Yearly numbers of ssc's are much better correlated with yearly averages of the sunspot numbers than with yearly averages of the magnetic activity, and the 27-day recurrence tendency is very small. There does not exist a semiannual variation of the occurrences. Also, there does not exist any daily variation of the occurrences, but at subauroral latitudes there exists an outstanding daily variation of the amplitudes. Furthermore, the small seasonal dependence at low latitudes in the daily variation reported by Maeda et al. (1964) is confirmed and the existence of a very large seasonal dependence at subauroral latitudes is pointed out. The previous interpretations of Obayashi and Jacobs (1957) and of Wilson and Sugiura (1961) are discussed in relation to some of these results.